Automatic test equipment (ATE) may be used to test microelectronic devices during production or in a quality assurance context. Some ATE systems may generate a test pattern and present the test pattern to inputs of a microelectronic device under test (DUT). The ATE may then measure or sense output responses from the DUT. A comparison of the test pattern presented at the DUT inputs and the output responses may thus comprise a DUT transfer function. The ATE may make quality and reliability judgements about the microelectronic device based upon the transfer function.
Clocking speeds associated with modern digital microelectronic devices may impose limitations on lengths of cables used to deliver the test pattern to the DUT. Impedances associated with connectors and excessively long cables may create undesirable timing shifts in the test pattern as applied to the DUT. Because of these constraints, it may be desirable to locate a compact test pattern generator portion of the ATE close to the DUT. However, the compact nature of the test pattern generator may preclude collocating all of the desired ATE processing functions at the test pattern generator.
As a result, some ATE may separate the test pattern generation and response collection functions from administrative and post-processing functions. An administrative host computer (AHC) may be connected to the test pattern generator in a master/slave relationship. The AHC may download test patterns to the test pattern generator and may collect test results periodically for analysis, reporting, and storage.
Some ATE systems may present test patterns under nominal conditions of operating voltages, timing, and temperature. Other ATE systems may be parametric. That is, they may be capable of varying voltage, timing, temperature, and other operational parameters incrementally as testing is performed. A parametric tester may download a set of values associated with a parameter to be varied from the AHC to the test pattern generator. The test pattern generator may vary the parameter according to the downloaded values as it repeatedly presents the test pattern to the DUT. Parametric ATE may thus provide insight into operational margins associated with the DUT. However, test times may increase as the test pattern generator pauses to receive new parameter values from the AHC.